Last year, New York had six zip codes on the list. This year, it has just three.

The reason for California's dominance? It's partly the deluge of tech money. Three of the four zip codes are in Northern California, near Silicon Valley, home to tech giants like Facebook and Google and their executives. But it also has to do with the types of homes.

"The thing about the Bay Area is that the housing supply is ridiculously constrained," Michael Simonsen, CEO of Altos Research, told Forbes. "And in a town like Atherton, there are no condos."

Manhattan, he added, has a mix of homes, from brownstones to high-rise condos.

To determine the ranking, Forbes works with Altos Research, a data provider, which looks at the asking prices — not sale prices — of single-family homes in 28,500 zip codes across America over a 90 day period ending Oct. 9.

Here are the 10 priciest zip codes in America. To see the complete list, visit Forbes.